This invention is generally directed to the field of disc drive assemblies; more specifically, to disc drives utilizing hydrodynamic motors. In particular, this invention relates to a disc drive assembly having a stiffened top cover which is configured to minimize the risk of contact of the top cover with the hydrodynamic motor.
Modern computers employ various forms of storage systems for storing programs and data. For example, various forms of disc drive systems have been designed to operate under the control of a computer to record information and/or retrieve recorded information on one or more recording discs. Such disc drives include hard disc drives which employ recording discs that have magnetizable (hard) recording material on a stiff or hard surface, optical disc drives which employ recording discs that have optically readable recording material, magneto-optical (MO) disc drives which employ recording discs that have optically readable magnetizable recording material, or the like.
Conventional disc drive systems typically include one or more recording discs supported for relatively high speed rotation on a rotary spindle. For example, FIG. 1 shows a side view of portions of a conventional disc drive system, including a conventional data storage or recording disc 200 supported on a spindle 210. A disc drive motor (not shown) is operatively coupled to the spindle 210 for rotation of the spindle and the disc supported thereon. A recording and/or reading head 220 is supported by suitable head support structure (not shown) adjacent the recording surface of the disc. To simplify the disclosure, FIG. 1 is shown with a single recording disc 200 having a single recording surface and a single head 220. However, other conventional disc drive systems employ multiple discs, double-sided discs (discs with recording surfaces on both surfaces) and multiple heads.
As shown in FIG. 1, the disc 200 has a central hub opening through which the spindle 210 extends. The disc 200 and spindle 210 are shown in a top view in FIG. 2. The spindle 210 extends through a central opening, which defines an inside diameter, of the disc. The disc is secured at its inner diameter (ID), in a fixed relation with the spindle 210, and is supported such that the outer diameter (OD) portion of the disc is free from contact with other components. In this regard, the disc is clamped at its ID to the spindle 210 and is free at its OD. When the spindle 210 is rotatably driven, the disc 200 is cause to rotate with the spindle. In many cases a top (not shown) which provides a protective cover for the disc is attached through the top of the spindle 210.
Typically, multiple center-open discs and spacer rings are alternately stacked on a spindle motor hub. The hub, defining the core of the stack, serves to align the discs and spacer rings around a common axis. Collectively the discs, spacer rings and spindle motor hub define a disc pack assembly.
The surfaces of the stacked discs are accessed by the read/write heads which are mounted on a complementary stack of actuator arms which form a part of an actuator assembly. Generally, the actuator assembly has an actuator body that pivots about a pivot mechanism disposed in a medial portion thereof. A motor selectively positions a proximal end of the actuator body. This positioning of the proximal end in cooperation with the pivot mechanism causes a distal end of the actuator body, which supports the read/write heads, to move radially across the recording surfaces of the discs, such that the head may be selectively positioned adjacent any recording location on the recording surface of the disc, as the disc is rotated.
In operation, the head 220 is moved in the radial direction to align or register with a desired track location on the recording surface of the disc. Once aligned or registered with the desired track location, the head 220 is operated to read or write information onto the recording surface at the desired track location. It is important to properly register the head 220 with the track location to effect accurate reading or writing operations on the registered track.
Modern advances in disc drive technology have resulted in increased disc storage density and decreased track widths, such that greater amounts of information may be stored per given recording surface area. However, as track widths decrease (and storage density increases), the need for accurate head registration increases. In general, smaller track widths require greater head-to-track registration accuracies and have smaller alignment error tolerances. For example, for a disc with 393.7 tracks per mm (10,000 tracks per inch), the track width is only about 2540 xcexcmm (100 xcexcin) and the total allowable (tolerable) off-track mis-registration may be no more than about 254 xcexcmm (10 xcexcm) peak-to-peak.
Track mis-registration (TMR) may result from a variety of sources, including, for example, ball bearing non-repeatable run out, spindle-disc rocking vibrations and disc flutter. In some larger motor environments, hydrodynamic motors have been used to avoid or minimize the asynchronous vibrations caused by ball bearing non-repeatable run out and rocking vibration. Accordingly, the assignee of the present invention employs a hydrodynamic motor instead of the ball bearing motors previously used in disc drive systems.
Although the introduction of the hydrodynamic motor can reduce vibration problems associated with conventional disc drive systems, introduced other concerns have been raised. For instance, the hydrodynamic motors are not attached to the top cover by the spindle. In fact, the motor, when spinning, cannot be touched by the top cover or else there is a risk of the head crashing the disc. A need in the industry exists for a top cover or top section of the housing which will decrease the risk of interfering with the spinning disc and rotor during use, for example, due to unforeseen, or foreseen, forces exerted on the top cover of the disc drive housing such that it depresses into the spinning disc. A force, for example, created by a person handling the disk drive.
Preferred embodiments of the instant invention are directed to a system apparatus and method involving a stiffened housing that for improved protection of a spinning rotor of a hydrodynamic motor and decreases the likelihood that the disc will fail due to interference with the operation of the motor. Preferred embodiments include a housing, a data storage disc, a head-arm assembly, which resides adjacent the data storage disc, and a controller, wherein the housing includes a base section and a top section which connect together to form an enclosure for further components of the disc drive apparatus, including the data storage disc (or disc stack). The data storage disc (or disc stack) is driven by a hydrodynamic motor that is disposed in the center of the disc.
The top section of the housing further includes a top surface and a plurality of side walls, wherein the top surface includes a first indented portion, a second indented portion, a raised portion and a plurality of coupling sites. The first and second indented portions are formed within the material of the top section and increase the stiffness of the top section by confining and minimizing the area of the top surface that will be distorted or bent when a force is applied thereto.
The raised portion of the top surface is disposed adjacent (directly above) the motor and helps prevent the top surface from contacting the motor. Similar to the first and second indented portions, the raised portion increases the strength of the top by minimizing the ability of the material of the top section to bend between the contours of the indented and raised portions.
To further minimize the distortion area, coupling sites are disposed on the top. The sites are located to maximize the lines of strength, which further increases the stiffness of the top section of the housing.
The indented portions and locations thereof on the top section of the housing are features of embodiments of this invention. These features provide a number of advantages, including minimization and confinement of the area of distortion or bending. A further advantage of these features is that the minimization of the distortion area allows for the maintenance of the integrity of the material forming the top.
As a further feature of embodiments of this invention, the load or strength lines formed in the top section are located to cross a portion of the motor. An advantage of this feature is that the placement of the load lines decreases the likelihood that the top surface will be depressed into contact with the motor during operation.
The above and other advantages of embodiments of this invention will be apparent from the following more detailed description when taken in conjunction with the accompanying drawings. It is intended that the above advantages can be achieved separately by different aspects of the invention and that additional advantages of this invention will involve various combinations of the above independent advantages such that synergistic benefits may be obtained from combined techniques.